Matching Cultivar to Nitrogen and Soil: A Diagnostic Framework for Closing Wheat Yield Gaps in the Huang-Huai Region

Closing yield gaps in wheat production requires optimized cultivar selection and nitrogen (N) management; however, the cultivar-specific responses to N fertilizer and soil fertility remain largely unquantified. Twenty-eight wheat cultivars were evaluated under three fertilization treatments (T) (CK, no-fertilizer; N1, 210 kg N ha−1 as single basal application; and N2, split-N at 105 + 105 kg N ha−1, applied only in 2022–2023 and 2023–2024) over three growing seasons in the Huang-Huai region. Two-way interactions (cultivar × T, cultivar × year, and T × year) and the three-way cultivar × T × year interaction were significant (p < 0.001), whereas the year main effect was not significant (p = 0.329). Fertilization accounted for the largest proportion of yield variance (η2 = 0.589), followed by cultivar × year (η2 = 0.244) and cultivar (η2 = 0.141). Yield ranged from 3435 to 5231 kg ha−1 (a 1.52-fold difference). Hierarchical clustering of basic soil productivity contribution rate (BSPCR) classified cultivars into high, moderate, and low soil fertility dependence classes, enabling fertility-based cultivar matching. Within-cultivar correlation analysis identified spike number as the predominant yield-limiting factor (71.4%). Based on composite scores integrating yield, stability, split-N response index (SNRI), and BSPCR, Tier I cultivars (C20, C1, C21, C14) are recommended for high-fertility fields with split-N application, combining high yield (5004–5231 kg ha−1), strong N responsiveness (SNRI ≥ 1.10), and high BSPCR; Tier II cultivars (C7, C3, C18, C12, C22) offer a balanced performance in yield and stability. The proposed tiered system—prioritizing Tier I and Tier II cultivars according to field fertility and production goals—provides an exploratory, site-specific framework for closing wheat yield gaps in the Huang-Huai region.